fig1

Figure 1. Intracrine androgen biosynthesis. Top panel shows reactions that occur in the adrenal reticularis. Bottom panel shows the conversion of adrenal steroids into the potent androgens testosterone and 5α-DHT in human prostate. The classical or canonical pathway is shown in red; the 5α-adione pathway is shown in blue; the backdoor pathway from allopregnanlone is shown in purple; the alternative pathway from 5-androstenediol is also shown. All enzymes are listed in italics by their gene names as follows: AKR1C1, 3α(20α)-hydroxysteroid dehydrogenase; AKR1C2, type 3 3α-hydroysteroid dehydrogenase; AKR1C3, type 5 17β-hydroxysteroid dehydrogenase; CYP17A1, 17α-hydroxylase17/20 lyase; HSD3B1, type 1 3β-hydroxysteroid dehydrogenase; HSD17B2 and 17HSD17B4, type 2 and type 4 17β-hydroxysteroid dehydrogenase; HSD17B6, type 6 17β-hydroxysteroid dehydrogenase and retinol dehydrogenase; and SRD5A1/2, type 1 and type 2 steroid 5α-reductase